Voice Packet Performance Estimation through Step Network Using OPNET Taskeen Zaidi, Nitya Nand Dwivedi Associate Professor, Research Scholar, Department of Computer Science, Department of Computer Science, SRM University (U.P.) 225003, India SRM University (U.P.) 225003 India, E-Mail:[email protected] E-Mail: [email protected] Abstract- VoIP transfer voice over networks such as LAN. of layers are well described [3]. A brief explanation of the This technology is growing rapidly due to support of terms bandwidth, latency, throughput is described in [5]. existing network infrastructure at low cost. Various The step topology model was validating by Zaidi and simulations have been done and it is observed that by Saxena [6] by using object oriented model based on increasing the VoIP client, packet length and traffic arrival UML.A state diagram was converted to FSM and test cases rate the performance of step network affected. In the were generating to validate step model for distributed current work packet dropped, packet received, voice traffic computing environment. Structural topology optimization sent and end-to-end delay is estimated for various queuing with benchmark studies was done [7]. The network disciplines like PQ, FIFO and WFQ. It is depicted that topology models, structures, basic abstraction principle queuing disciplines effects the applications performance using graph theory, network topologies characterization and utilization of resources. and approaches for modeling the topology on internet was well explained by Wahlisch [8]. The performance of step topology [9] was measured by transferring large size audio Keywords—Performance, Queuing Discipline, and video packet in bytes through simulation tool. The OPNET,PQ,WFQ,FQ performance of step topology was estimated on a simulation tool by Zaidi and Dwivedi [10] through various I. INTRODUCTION queuing disciplines implemented on routers and it was Queuing disciplines are implemented at the router. A good observed that for normal packet transfer over a network queuing discipline treats packet transfer in a fair and FIFO is best and for large packet size transmission and real efficient manner that will be helpful to improve the quality time interactive packet PQ and WFQ is best. Transition of service. As FIFO is based on first in first out so it is mechanism was implemented and simulated by authors quite similar to queue waiting at the bus stop for bus. PQ [11] according to organizational demand and a manual offers priority to real time packet transfer whereas WFQ tunnel was created for secure data communication and it offers weight and priority both to the packets. was depicted that tunnel provides better QoS to the ISP’s, Data centres for packet transmission.1 II RELATED WORK A method for identification of recurring patterns in various III. BACKGROUND platform independents environment is represented [1]. The A. Step Topology performance of virtualized network is estimated A new topology called as step topology for static interconnection of handheld devices in steps as desktop computer systems, automatically on various hardware with efficient resources utilization. The WSN algorithms are modeled and analyzed Figure 1. OPNET Representation of VoIP Step Network mode by using some techniques and then these techniques are applied to estimate the performance and checking Optimal Geographical Density Control (OGDC). The Monte Carlo simulation is further used to estimate OGDC. The simulation was done on 800 sensor nodes and the results were compared on NS2 simulation tool [2]. 978-1-5386-6227-4/18/$31.00 ©2018 IEEE A brief overview of networks, networks architecture, topologies, protocols, models, layers, techniques, functions 1 latency in a network. Some of the queuing disciplines are as FIFO,PQ and WFQ. laptops, mobile, etc. This topology is modification of bus A. FIFO topology and by varying the steps we interconnect N numbers of computer systems. This topology works well if the link between In this the packet first put in the queue will be first transmitted. As two computers connected through bus topology fails. In this the router buffer space is of finite size, so when the buffer will full topology if individual node is busy then tasks can be executed on the packet will be discarded. This mechanism doesnot prioritize next node by using message passing technique in distributed the packet transmission in a network. This queuing mechanism is manner and the devices can be connected in static as well as not suitable for real time applications. dynamically in adhoc manner. A view of step topology through OPNET simulation tool is shown in figure 1. The detailed overview about step topology can be found in [4]. B. PQ This is a variation of FIFO queuing discipline and it marks the packet with the priority indicating in ToS field. In this queuing discipline multiple FIFO queues are implemented at router with a B. OPNET Modeler priority class. The packets are sorted in the buffer. The highest Optimized network engineering (OPNET) tool is used to simulate priority packet will be transmitted first.It is best suited for real the performance of the network . It has inbuilt models, protocols time applications like VoIP. As higher priority packet will get and devices that create and simulate different networks. It is a transmitted first so normal packet will go to long wait in buffer open software which has features like applications and starvation situation arises. troubleshooting, protocol modeling, traffic modeling, validation of application, estimating performance of complex network systems. It has discrete event simulation workflow that helps in C. WFQ creation, import, and configuration of topologies as well as WFQ assigns weight to each flow. The ToS field is used to network traffic and is also published results with statistics report. identify the weight. It is a combination of PQ and FQ. In this Key features of OPNET are: queuing discipline packets are weighted so that lower bandwidth (i) Network model. packet gets higher priority. WFQ supports real time interactive (ii) Process Modeling applications by putting traffic in front of queue with higher weight (iii) Simulation kernel and lower bandwidth packet transmitted in smaller time. Some (iv) Event based simulation. time it is inefficient as it increases congestion state in a network. (v) Link modeling. V.PERFORMANCE To simulate performance of various scheduling techniques for Performance of network is used to measures of service quality for VoIP, the architecture of step network is shown in Table 1. transferring data from source to destination. There are some Table 1. List of Events for Transition Table parameters that classify the performance of network as shown in figure 2: Application ToS Description Connected to routers by 10 BaseT (10 Mbps) FTP and Best effort(0) links. Figure 2. Performance parameters VoIP nodes A. Bandwidth PCM Quality It is the capacity to transmit the amount of data from one point to Speech” for voice, “Interactive another in a given amount of time as shown in figure 3. The bandwidth measure data transfer rate. Bandwidth is usually VoIP application Intercativevoice(6) measures in bites per second and bytes per seconds for digital Voice. communication[12]. IV.Queuing Disciplines For resources allocation management, routers in a network implements queuing disciplines so that packets waiting to be transmitted must buffered. The queuing discipline controls the packet transmission as well as packet dropped. It also effects the Figure 3. Manufacturing Internet Bandwidth[12] E. Error Rate It is the key parameter for measuring the performance of a network. It measures number of errors encountered due to noise during data transmission over a connected network as shown in B. Throughput figure 7. If the error rate of any network is high than the network Throughput is amount of data that will be transmitted from one performance will be degraded and it will become less reliable for point to other in a given amount of time as shown in figure 4.. It is packet transmission[16]. used to measure the network performance[13]. It may also define as the successful transmission of a message over a communication channel. Figure 7. Error rate[16] Figure 4. Throughput[13] C. Latency VI.SIMULATION RESULTS Latency or delay is the situation arises during processing or A. Ethernet Delay transmitting data over a network as shown in figure 5. The network latency occurs due to delay in data communication In case of FIFO, there is only one queue having size of 500 process or transmission[14]. The latency effects the network packets and as FIFO processed the packet on first come first serve performance. basis and there is no priority for individual type of incoming traffic. When more packets arrive, then they get stored in a waiting queue and if queue becomes full the incoming packets will be discarded. In WFQ packets dropped occur due to congestion in network state. In PQ the priority is higher for voice packets than WFQ and FIFO as shown in figure 8. In case of PQ, Voice packets are assigned highest priority. After voice, video packets get priority than normal packets. Voice traffic has supreme priority so they are transmitted as soon as received, and video and normal traffic has to wait when there is Figure 5. Latency[14] incoming voice packets. Again video traffic has priority over FTP in PQ. D. Jitter As WFQ handles shared buffer and when buffer gets overloaded congestion situation arises, now interface enforced queue to be limited. When congestion occurs voice packet has to wait as video packets causing packet loss as queue becomes full which is opposed to PQ where voice traffic has higher priority and need not to be waiting. So overall observation is FIFO has higher packet dropping and WFQ has semi lower and PQ is lower. Jitter is a condition that occurs due to variation in packet arrival time s shown in figure 6.